1. Technical Field
The disclosure relates to a controlling circuit with a power saving mechanism and an erroneous wake-up preventing mechanism and method thereof.
2. Description of the Prior Art
For current physical layers, data rates of a network connection have increased from 10 Mb/s to 100 Mb/s and 1000 Mb/s. In order to have downward compatibility with previous data rates, IEEE (Institute of Electrical and Electronics Engineers) standard 802.3-2005 supports three data rates (10 Mb/s, 100 Mb/s and 1000 Mb/s). Before two Ethernet physical layers are linked, an auto-negotiation is processed to confirm the highest data rate supported by these two Ethernet physical layers, and then the two Ethernet physical layers try to establish a link at this highest data rate. In addition, the IEEE 802.3az Energy Efficient Ethernet (EEE) standard provides a standard procedure to save the power of a network device when the Ethernet is in the Idle Mode. Conventionally, the two network devices have to perform the process of auto-negotiation to confirm if both network devices conform to the IEEE 802.3az EEE standard; however, most network devices do not support this auto-negotiation capability.
In a data transmitting system, when a first application circuit is linked to a second application circuit via a data transmitting medium, the first application circuit does not always exchange data with the second application circuit. For example, the first application circuit may continuously receive data from the second application circuit and does not transmit data to the second application circuit in a specific time interval, or no data is transferred between the first application circuit and the second application circuit. More specifically, when a transmitter of the first application circuit does not transmit data to the second application circuit, the transmitter of the first application circuit should stay in a low power consumption mode, or when a receiver of the first application circuit does not receive data from the second application circuit, the receiver of the first application circuit should stay in a low power consumption mode. Furthermore, when the data capacity transferring between the first application circuit and the second application circuit is small, the first application circuit and the second application circuit may also be operated in the low power consumption mode, e.g., a low data rate mode. The power saving mechanism of the first application circuit may differ from the power saving mechanism of the second application circuit, or only one application circuit has the power saving mechanism. In these situations, when one of the application circuits (e.g., the first application circuit) satisfies the condition to enter the low power consumption mode (e.g., the first application circuit does not receive data), the receiver of the first application circuit may not be able to enter the low power consumption mode due to the lack of a standard operating procedure for the first application circuit and the second application circuit.
In addition, when both receivers of the first application circuit and the second application circuit are operated in the low power consumption mode (e.g., a sleep mode), and when the receiver of the first application circuit transmits a triggering signal to the receiver of the second application circuit via the data transmitting medium to wake up the receiver of the second application circuit from the sleep mode, an echo may be reflected to the receiver of the first application circuit. The receiver of the first application circuit may also be woken up from the sleep mode by the echo. In other words, the receiver of the first application circuit is erroneously woken up, which means an error may occur in the data transmitting system. Therefore, providing a standard power saving mechanism for the data transmitting system to save the power of the network device, and providing a wakening mechanism to properly wake up a network device from the low power consumption mode is a significant concern in the communication system field.